The decision, simplified
If you’re replacing a packaged rooftop unit in 2026 in a cold-climate commercial building, you have three real options:
- All-gas RTU. Cheapest first cost, highest operating cost, growing BPS exposure.
- Dual-fuel RTU. Heat-pump for most operation, gas backup. Best TCO in many cold climates today.
- All-electric heat-pump RTU. Best decarbonization story, growing BPS value, highest operating cost in cold climates with current gas rates.
For our analysis we’re putting a 100-ton RTU replacement in Denver (ASHRAE Climate Zone 5B), with typical commercial occupancy and a 20-year planning horizon.
The TCO model
Year-1 capital costs (installed, with controls and electrical work, before incentives):
| RTU type | Installed cost | Year-1 operating cost |
|---|---|---|
| All-gas | $185,000 | $42,000 |
| Dual-fuel (HP + gas) | $245,000 | $27,500 |
| All-electric HP | $235,000 | $31,000 |
Operating cost assumptions: $0.115/kWh blended electric (Xcel Colorado commercial), $0.85/therm gas, COP curves derived from manufacturer performance data for current-generation R-454B equipment.
20-year nominal TCO, no escalation:
| RTU type | 20-yr operating | Total TCO |
|---|---|---|
| All-gas | $840,000 | $1,025,000 |
| Dual-fuel | $550,000 | $795,000 |
| All-electric HP | $620,000 | $855,000 |
With 3% real annual escalation for gas, 1.5% for electric (closer to current forward curves):
| RTU type | 20-yr operating | Total TCO |
|---|---|---|
| All-gas | $1,128,000 | $1,313,000 |
| Dual-fuel | $682,000 | $927,000 |
| All-electric HP | $719,000 | $954,000 |
The dual-fuel/all-electric gap is ~$27,000 over 20 years at these assumptions. That’s the size of one year of routine maintenance. It’s noise.
Where the breakpoints actually move
The TCO comparison flips on three variables. Sensitivity:
Gas escalation. At 5% real gas escalation, all-electric ties dual-fuel by year 12 and wins by year 20 by ~$60,000. At 7%, all-electric wins outright with no other adjustments.
Time-of-use electric rates. Most Colorado commercial customers don’t yet face genuine TOU pricing, but it’s coming. If the building can shift heat-pump heating to off-peak (overnight precooling/preheating with thermal mass), the all-electric premium narrows further.
BPS exposure. This is the variable most owners undercount. If your building is over 50,000 sq ft in Colorado, you have BPS exposure. The economic value of EUI reduction toward the 2030 target is real even though it’s not on the utility bill. For most building types, the implicit value of avoiding the EUI delta that dual-fuel produces vs all-electric is $8,000–$15,000/year by 2028, depending on how the asset is priced (lease underwriting, sale comps, ACP costs).
Add that to the all-electric column and the comparison flips clearly.
Refrigerant: the part nobody is talking about enough
The bigger 2026 decision for most owners isn’t dual-fuel vs all-electric — it’s making sure whatever you spec is on R-454B, not R-410A.
R-410A production phase-down under the AIM Act began in 2024. By 2027 it gets expensive. By 2030 it gets uncomfortable. Specifying a new R-410A RTU in 2026 is locking yourself into a service-and-replacement headache for the next 15 years.
R-454B (and other A2L refrigerants like R-32) are the replacement. They are mildly flammable, which means:
- Charge-size limits (typically ~12 kg per system in most jurisdictions).
- Leak detection requirements in occupied spaces below the equipment.
- Updated installation codes (the relevant ASHRAE 15 and IMC updates have caught up).
- Some retrofit considerations if the existing system is being reused.
Most major OEMs (Carrier, Trane, Daikin, Lennox, AAON) have full R-454B product lines for commercial RTUs as of mid-2026. Spec the new refrigerant.
Hybrid utility rates
Worth mentioning because they materially change the answer in Colorado: Xcel has piloted dual-fuel-optimized commercial rates that align with how dual-fuel equipment should run. The smart controls on modern dual-fuel RTUs can switch between heat-pump and gas operation in real time based on the relative cost of operation. With these rate structures, dual-fuel TCO improves another 5–10%.
If your utility offers anything like this, model it. If they don’t, ask about it. These rates are coming nationally; getting on one early can be worth the application paperwork.
What we’re advising owners
For most cold-climate Colorado commercial buildings in 2026:
- Buildings under 50,000 sq ft (no BPS exposure): dual-fuel RTU is the right answer on pure TCO.
- Buildings 50,000+ sq ft (BPS exposure): all-electric heat-pump RTU is increasingly the right answer when BPS value is properly priced.
- Either way: spec R-454B equipment, lock in 179D positioning before June 30, 2026 if at all possible, and design control sequences that can adapt to TOU/dual-fuel rate structures whether you’re on one yet or not.
For mild-climate markets (CZ 3, 4), all-electric is increasingly the default.
What we got wrong on a project last year
On a 78,000 sq ft Colorado office in 2025, we spec’d dual-fuel for the rooftop replacement program. TCO model said dual-fuel. Customer was happy with the math. We commissioned the systems in late 2025.
Six months later, the customer’s lender priced BPS exposure into the refinancing terms in a way nobody saw coming. The dollar value of the implicit EUI reduction we would have gotten with all-electric was material — and we had locked in dual-fuel equipment for 20 years.
The lesson: TCO models that ignore BPS-implied value were already wrong in 2025. They’re more wrong in 2026.
Sources
- ASHRAE Climate Zone reference (90.1 Climatic Data Tables)
- Xcel Colorado commercial rate tariffs (current as of Q2 2026)
- AIM Act refrigerant phase-down schedule (EPA)
- ASHRAE Standard 15 (Safety Standard for Refrigeration Systems)
- DOE Heat Pump RTU Considerations (Better Buildings Solution Center)
- Slipstream RTU electrification market analysis (slipstreaminc.org)
- AAON, Trane, Carrier R-454B commercial RTU performance datasheets
Frequently asked questions
What is a dual-fuel RTU?
When does an all-electric heat-pump RTU make sense?
Why does R-454B matter for this decision?
What's the typical first-cost premium for dual-fuel vs all-gas RTU?
How does this interact with BPS targets?
What about hybrid utility rates?
Chris Mbori
Founder of Eenovators Limited (East African ESCO), partnering with AIM Dynamics. Built Eagles and the ADM portal. AEE Energy Manager of the Year (Sub-Saharan Africa). 10 AEE certifications. Licensed Engineer. Field journal — hype-skeptical, field-tested.